88 lines
3.2 KiB
Text
88 lines
3.2 KiB
Text
/-
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Copyright (c) 2024 Joseph Tooby-Smith. All rights reserved.
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Released under Apache 2.0 license as described in the file LICENSE.
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Authors: Joseph Tooby-Smith
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-/
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import HepLean.SpaceTime.LorentzVector.Complex.Two
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import HepLean.SpaceTime.MinkowskiMetric
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/-!
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# Metric for complex Lorentz vectors
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-/
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noncomputable section
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open Matrix
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open MatrixGroups
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open Complex
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open TensorProduct
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open SpaceTime
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open CategoryTheory.MonoidalCategory
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namespace Lorentz
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/-- The metric `ηᵃᵃ` as an element of `(complexContr ⊗ complexContr).V`. -/
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def contrMetricVal : (complexContr ⊗ complexContr).V :=
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contrContrToMatrix.symm ((@minkowskiMatrix 3).map ofReal)
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/-- The metric `ηᵃᵃ` as a morphism `𝟙_ (Rep ℂ SL(2,ℂ)) ⟶ complexContr ⊗ complexContr`,
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making its invariance under the action of `SL(2,ℂ)`. -/
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def contrMetric : 𝟙_ (Rep ℂ SL(2,ℂ)) ⟶ complexContr ⊗ complexContr where
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hom := {
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toFun := fun a =>
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let a' : ℂ := a
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a' • contrMetricVal,
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map_add' := fun x y => by
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simp only [add_smul],
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map_smul' := fun m x => by
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simp only [smul_smul]
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rfl}
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comm M := by
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ext x : 2
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simp only [Action.instMonoidalCategory_tensorObj_V, Action.instMonoidalCategory_tensorUnit_V,
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Action.tensorUnit_ρ', CategoryTheory.Category.id_comp, Action.tensor_ρ', ModuleCat.coe_comp,
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Function.comp_apply]
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let x' : ℂ := x
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change x' • contrMetricVal =
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(TensorProduct.map (complexContr.ρ M) (complexContr.ρ M)) (x' • contrMetricVal)
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simp only [Action.instMonoidalCategory_tensorObj_V, _root_.map_smul]
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apply congrArg
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simp only [Action.instMonoidalCategory_tensorObj_V, contrMetricVal]
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erw [contrContrToMatrix_ρ_symm]
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apply congrArg
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simp only [LorentzGroup.toComplex_mul_minkowskiMatrix_mul_transpose]
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/-- The metric `ηᵢᵢ` as an element of `(complexCo ⊗ complexCo).V`. -/
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def coMetricVal : (complexCo ⊗ complexCo).V :=
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coCoToMatrix.symm ((@minkowskiMatrix 3).map ofReal)
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/-- The metric `ηᵢᵢ` as a morphism `𝟙_ (Rep ℂ SL(2,ℂ)) ⟶ complexCo ⊗ complexCo`,
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making its invariance under the action of `SL(2,ℂ)`. -/
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def coMetric : 𝟙_ (Rep ℂ SL(2,ℂ)) ⟶ complexCo ⊗ complexCo where
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hom := {
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toFun := fun a =>
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let a' : ℂ := a
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a' • coMetricVal,
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map_add' := fun x y => by
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simp only [add_smul],
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map_smul' := fun m x => by
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simp only [smul_smul]
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rfl}
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comm M := by
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ext x : 2
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simp only [Action.instMonoidalCategory_tensorObj_V, Action.instMonoidalCategory_tensorUnit_V,
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Action.tensorUnit_ρ', CategoryTheory.Category.id_comp, Action.tensor_ρ', ModuleCat.coe_comp,
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Function.comp_apply]
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let x' : ℂ := x
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change x' • coMetricVal =
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(TensorProduct.map (complexCo.ρ M) (complexCo.ρ M)) (x' • coMetricVal)
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simp only [Action.instMonoidalCategory_tensorObj_V, _root_.map_smul]
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apply congrArg
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simp only [Action.instMonoidalCategory_tensorObj_V, coMetricVal]
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erw [coCoToMatrix_ρ_symm]
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apply congrArg
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rw [LorentzGroup.toComplex_inv]
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simp only [lorentzGroupIsGroup_inv, SL2C.toLorentzGroup_apply_coe,
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LorentzGroup.toComplex_transpose_mul_minkowskiMatrix_mul_self]
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end Lorentz
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end
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